It is generally known to fabricate boat or ship bodies with a length from about 8 meters to about 20 meters using glass fiber reinforced plastic materials of various types by various fabrication techniques, including molding techniques, lay-up techniques, and spray-on application for example, in series mass production. On the other hand, hulls for ships or boats of this size category can also be conventionally fabricated using aluminum-based materials, but such metal boat hulls are typically fabricated one-off, i.e. one at a time, and largely by hand using many individual manual operations for assembling and finishing the metal components. Disadvantageously, the manual operations lead to inconsistencies or deviations, and the generally required welding operations can lead to warping and displacement of the components from the required contours and positions. Also, this manner of construction often requires jigs, clamps or fixtures that are temporarily welded onto the hull components for holding the components in place during fabrication, and that are later removed. These factors all give rise to a relatively high degree of required rework, post-work and finishing work to achieve the required finished contours and smooth fair surfaces. Namely, achieving the required hydrodynamic contour and smooth fair surface of such a boat hull of an aluminum-based material often requires considerable expense and effort in the need for grinding off weld beads, temporary weld locations, deformed contours, and the like, and smoothing such areas through the application, shaping and finishing of putty or mastic. In such cases, the thickness of the applied synthetic putty or mastic may actually even exceed the sheet metal thickness of the aluminum-based material of the hull skin or planking. This disadvantageously increases the weight of the hull by the weight of the applied putty or mastic, and also requires significant additional work. Furthermore the applied non-aluminum putty or mastic materials sharply limit the otherwise advantageous recyclability of the aluminum-based material of the hull. Thus, it is desired to provide a hull construction of aluminum-based material that avoids the need for non-metal putty or mastic and especially also avoids warping or deformation of the metal components during the fabrication.
The published French Patent Application having Publication Number FR 2 408 508 discloses a ship or boat body of the general type mentioned above, which has a hull made of several planks of an aluminum alloy that are welded together. For a boat hull length of approximately 10 to 12 meters, the thickness of the aluminum alloy sheets to be used for manufacturing this hull is at least 12 mm and is particularly selected so that the hull is structurally strong and form-stable without any transverse frame or rib elements, and can be used as such. However, there is a substantial weight disadvantage that results due to the significant thickness that is required of the aluminum alloy planks in such a manner of construction. Furthermore, the fabrication process is complicated because special forms or jigs as well as special welding devices are necessary for holding and clamping or tacking the planks in the required position while the welding is carried out.
Additionally, the published European Patent Application having Publication Number EP 0 049 871 discloses a boat hull that is assembled from plank-like aluminum profiles, which are pre-bent or pre-curved corresponding to the desired hull shape, and then the planks are joined with one another. Particularly, the individual planks have shank-like or flange-like projections that extend in the boat's longitudinal direction along the edges of the planks and that are screwed together with one another in order to connect adjacent planks.
Furthermore, U.S. Pat. No. 4,917,037 discloses a boat or ship body with a hull of metal, particularly aluminum, and an inner or upper structure of fiberglass. The fiberglass inner structure is set into and joined to the aluminum hull structure along an exterior perimeter edge of the hull forming a gunwale. The hull has a typical conventional kinked rib or bent rib cross-section, with a chine-like intermediate portion between the sidewall portion and the bottom portion of the hull. In addition to the outer skin, the hull further includes regularly spaced transverse frames or ribs as well as longitudinally extending stiffening beams or stringers. Particular construction details of the aluminum hull and its assembly are not disclosed.
The internet webpage http://www.kastenmarine.com/frames_first.htm includes a discussion of various different methods for fabricating boat hulls of aluminum. Particularly, that webpage discloses a fabrication method called the “plate-first” method, which uses a 3D-CAD model, by which the metal plates that form individual plank elements are pre-cut corresponding to their respective desired perimeter configuration or developed plan form, and then so arranged that they are anchored one after another on specialized jigs or holding devices in the respective proper positions, where they are clamped or tacked and finally welded together with one another. According to the method described in this internet webpage, this process can be carried out without the use of a transverse rib framework. Instead, in such a known manner of assembling a boat hull, the transverse rib framework is only later inserted into and welded onto the hull planking or skin that has first been fabricated by itself as discussed above. A significant advantage of such a construction technique is that it can largely avoid the above mentioned undesirable deformations of the aluminum outer skin of the hull, which can otherwise arise when aluminum plank elements are welded to the respective allocated transverse ribs.
Furthermore, the above mentioned internet webpage http://www.kastenmarine.com/frames_first.htm, with regard to so-called single-chine hull shapes, mentions the advantage that the sheet metal plates used as plank elements for constructing such boat hulls do not need to be rolled or otherwise deformed before the assembly or construction of the hull. This article also mentions that it is possible to weld the rib or frame elements onto the plank elements before the assembly thereof.
All of the above discussed known fabrication methods require various auxiliary structures and devices, on the inside and/or on the outside of the hull, in order to carefully and sufficiently hold or tack the planking plates in place for then carrying out the welding. It would be desirable to reduce or eliminate the need for such auxiliary structures, holding devices, jigs, clamps, and other fabrication accessories, so as to simplify the fabrication process and thereby reduce the costs.